Lawn mowing machines include cutting blades that are attached to a shaft, such as a crankshaft, within the mowing machines that rotate at high speeds for cutting grass. In operation, a mowing machine engine powers the crankshaft to rotate, which in turn rotates the cutting blade that is secured to the crankshaft. Thus, the crankshaft can become damaged when the cutting blade encounters or strikes an obstructive object, for example a rock, because rotation of the blade is interrupted and in some instances the object can completely prevent rotation of the blade and the crankshaft. Meanwhile, the engine continues to attempt to overcome this force, which can lead to damage to the engine and overheating. Furthermore, the crankshaft can become bent after striking an object such as a rock, which requires straightening by a technician that leads to lawn mower downtime.
Previous solutions to such problems have included attaching breakaway or yieldable blade tips to a cutting blade in a fixed manner to the rotating crankshaft. Although these blade tips may yield to an obstructive object, the blade tips continue to repetitively strike the object, thereby causing damage to the blade tips that can make the blade tips dull. Also, the cutting blade is still fixed to the rotating shaft in an unyielding manner, thereby continuing to strain the engine as it continues to attempt to overcome the resistive force applied by the object.
Therefore, it would advantageous to employ a cutting device that includes a cutting blade coupled with a base member such that the cutting blade can retract within the base member to form a blunt object when striking an object to prevent damage to the blade tip. The cutting blade can also pivotably disengage from the crankshaft when the cutting blade retracts to thereby prevent strain on the crankshaft to avoid overheating and damage to the mower engine.